boyfriend's mama hates me without cause?

my “boyfriend” (we arent dating because of his mom…) is 19 he lives with his mom,sister,step dad, and step sister. he goes to visit his dad and step mom every weekend. He acts like we are dating and tells me he likes me but that he cant date me. He was walking with me at one of our last home football games and his mom flipped out and started yelling at him to stay away from me. Im 16. him and i dated my freshman year for 6 months but we broke up. im now a junior and he is a senior. His mom is perfectly fine with his sister being around me(shes 11) and his step father amd his dad both like me. but his mother glares at me everytime I see her. I dont know what to do because she blows him off everytime he tries to say something about it. she wont let him do anything that might involve me and now im manageing the wrestling team at school and he is team captain so we are forced to talk… she is deffinately not pleased. shes always talking about how much she loves his exgf which happened to be one of my best for like 4 years(then we got into a huge fight) anyways…. I dont know how to make his mom like me if he wont stick up for me everyone else does and she still hates me. I guess he thinks if her ex husband her current husband and her daughter cant make her like how does he have a chance? What do Ido? I need advice…. :( I have been best friends with him for 5 years and i have liked him since the day we met… I honestly think I love him…